As I said, piracy will eventually extend to the theft of energy or raw matter. Carbon, silicone and iron are easy to come by in space. Actually, given that oli

As I said, piracy will eventually extend to the theft of energy or raw matter. Carbon, silicone and iron are easy to come by in space. Actually, given that olivine may be a common material in asteroids you're looking at abundant magnesium, iron, silicone and oxygen right there. However things like rare earth metals may be less easy to come by and if 3D printing jumps to molecular printing, then there'll be ships carrying pure metals as goods. Consider Neodymium cost averages $350/kg, a ship hauling it out to Neptune will be worth a lot of money stolen. Especially when the pirates would be selling for <$300/kg. If piracy happens over raw materials, eventually so will war even if it's just to stop the pirates. However there'll be asteroids found with thousands of tonnes of easily mineable rare metals, and then we'll see space battles.